Contact lithography, such as photographic contact lithography and imprint lithography, is a lithographic methodology that employs a direct or physical contact between a pattern tool and pattern receiving material on a substrate. In photographic contact lithography, for example, the pattern tool is a photomask. Physical contact is established between the photomask and a photosensitive layer on the substrate. During the physical contact, radiation passes through the photomask and exposes the photosensitive layer. As a result, a pattern of the photomask is transferred to the substrate. Imprint lithography, on the other hand, involves the formation of a relief pattern in material that is carried on the surface of a substrate. In one type of imprint lithography process, the pattern tool is a template (or “mold”) with a relief pattern. The template is brought into contact with a material on a substrate that is in liquid form at room temperature, or that is liquefied by heating. The liquid material fills the template and assumes the shape of the relief pattern. The material is then subjected to conditions that cause the material to solidify and the template is removed. A structure in the shape of the relief pattern will then remain on the substrate.
One important aspect of contact lithography is the alignment of the pattern tool and the substrate. The alignment process typically involves holding the pattern tool a small distance from the substrate while lateral and rotational adjustments (such as X-Y translation and/or angular rotation) are made. The pattern tool is then brought in contact with the substrate to perform the lithographic patterning.
Deformation-based contact lithography techniques, which involve the use of a spacer between the pattern tool and the substrate, as well as deformation that results in pattern tool/substrate contact, have been proposed in order to facilitate proper alignment. In particular, deformation-based contact lithography techniques insure that the pattern tool and substrate are mutually parallel and proximal during the alignment process, and reduce the likelihood that there will be a drift or slip in the relative positioning of the pattern tool and substrate as the pattern tool and substrate are brought into contact with one another after alignment. These advantages notwithstanding, the present inventors have determined that deformation-based contact lithography is susceptible to improvement.